It's a preliminary plan, but here's the general idea.
Week 1: I drive Erin and Noah to Calgary. Stay overnight at motel. Noah has a lesson early the next morning and then he and I drive home. Erin stays for four days at her teachers' home getting at least two violin lessons and possibly a piano lesson (with whom? no idea...), accompaniment session, recital etc., then comes home on the overnight bus. She arrives in time for choir, and can take part in Summit Strings.
Week 2: Erin is home, attends the school's Facilitated Learning Lab part-time. Practices her brains out, attends choir, accompanies at group class, plays in the community orchestra.
Week 3: Erin buses to Calgary, spends four days, repeating the lessons and other sessions. Buses home, does choir and Summit Strings.
Week 4: Repeat of Week 2.
Bus schedules are not ideal, but workable. I'll be doing an extra 10 hours of driving a month to get her to and from towns served by bus routes. Will it kill me? Who knows. I'll still only be driving to Calgary once a month at most, for Noah's lesson. I'll be spending one day a month less in Calgary too, saving a night at the motel, since we'll be doing the turnaround the same day. She'll be able to continue all her local activities with the exception of Community Choir. It's a sacrifice she's willing to make even though she loves that choir. Will this work for her Calgary teachers/billeting family? They seem more than willing to have her, amazingly, generously enough.
She's very excited about this plan. Lots of discussing, exploring and arranging left to do, but this is a post which has only three question marks, so that's some sort of progress.